Fault tolerant PLC system using CPU and I/O redundancy with switch over logic system for nuclear instrumentation

Nuclear instrumentation in power plants and fuel reprocessing plants demand very high reliable fault tolerant programmable logic controllers (PLC) since it is directly related to hazardous operation involving safety of plant, operator and in turn public at large. Components of control systems can fail depending on the circumstances and level of preparedness in plants, leading to a minor or major disaster. Utilizing existing technology and configuring system architecture, a fault tolerant PLC can provide superior solution to meet some of the challenges like high reliability, integrity and availability. This paper presents the background, concepts and implementation of fault tolerant PLC architecture using CPU and I/O redundancy with switch over logic system for nuclear instrumentation. (author)